Publicação
Genetic diversity and molecular responses to drought stress in Vigna unguiculata L. Walp.
| Resumo: | Climate change is considered as one of the major threats to agriculture sustainability and biodiversity. Drought is a severe environmental stress with major impacts on plant development and productivity. The use and improvement of crops with the ability to mitigate the effects of drought will be a key step for future crop sustainability. Cowpea (Vigna unguiculata L. Walp) is a warm-season grain legume, considered as an interesting crop, due to its high adaptability to heat and drought, as well as to its association with nitrogen fixing rhizobia. As other legumes, cowpea plays a major role in the global food security by providing an affordable dietary source of nutrients mainly proteins. The thesis main objective is to contribute for a higher cowpea production in Europe, anticipating the upcoming climate changes. To achieve this goal, multidisciplinary approaches were undertaken involving field trials and molecular genetics, physiology and biochemistry approaches. Regarding genetic diversity, the morphological and agronomical characterization of 24 Iberian Peninsula cowpea genotypes was performed, thus emphasizing the high genetic diversity among genotypes. From this characterization, ten cowpea genotypes were selected and further used for determining the stability of morphological and agronomical traits in three different environments (two in Portugal and one in Spain), during two consecutive years. A high interaction between genotype and environment was found and Elvas (Portugal) revealed to have the most appropriated environment for the production of this set of cowpea genotypes. The recently developed Cowpea iSelect Consortium Array (Illumina, Inc.) provided an excellent opportunity for further determination of cowpea genetic diversity. This array contains 51,128 SNPs and was used in a set of 96 cowpea genotypes, 43 of which from Iberian Peninsula and 23 from 22 other worldwide countries. Cowpea genotypes were clustered in four subpopulations, mainly differentiated by their geographical origin, allowing the suggestion of a new hypothesis about cultivated cowpea dispersion routes. Most of Iberian Peninsula genotypes and those from other Southern European and Northern African countries were grouped in the same subpopulation, indicating a high genetic similarity among them. However, three Iberian Peninsula cowpea genotypes did not belong to this subpopulation, being two of them classified as ‘admixed’ and another from a different subpopulation. These genotypes could be considered as interesting sources of diversity for future cowpea breeding programs. To get new insights on cowpea drought stress responses, the selection of the best approachesfor screening cowpea genotypes with enhanced drought tolerance is fundamental. Four cowpea genotypes (two Portuguese and two international tolerant references) were submitted to three different watering regimens, during 15 days. Several physiological, biochemical and molecular approaches were tested, revealing that stomatal function parameters, free proline and anthocyanins contents were the most effective in discriminating cowpea tolerance levels. Furthermore, two drought-related genes (VuCPRD14 and VuHsp17.7) were identified as the most effective for drought tolerance selection. For screening cowpea genotypes with enhanced drought tolerance, a worldwide collection of cowpea genotypes (58 genotypes) was tested for seed germination, seedling emergence and proline content under different osmotic potentials. A total of seven drought tolerant genotypes were suggested, which could represent starting material for future cowpea breeding programs. This thesis gave a good contribution for increasing cowpea production in Europe, being the selection of more productive and drought tolerant genotypes the first step. These genotypes could be integrated into breeding programs for enhancing cowpea resilience to climate change. Furthermore, the methodologies tested and proposed in this study allow an effective and fast screening of cowpea genotypes drought tolerance. |
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| Autores principais: | Carvalho, Márcia Raquel Gomes de |
| Assunto: | cowpea genotypes morphological and agronomical traits SNP markers drought stress screening methods |
| Ano: | 2018 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Trás-os-Montes e Alto Douro |
| Idioma: | inglês |
| Origem: | Repositório da UTAD |
| Resumo: | Climate change is considered as one of the major threats to agriculture sustainability and biodiversity. Drought is a severe environmental stress with major impacts on plant development and productivity. The use and improvement of crops with the ability to mitigate the effects of drought will be a key step for future crop sustainability. Cowpea (Vigna unguiculata L. Walp) is a warm-season grain legume, considered as an interesting crop, due to its high adaptability to heat and drought, as well as to its association with nitrogen fixing rhizobia. As other legumes, cowpea plays a major role in the global food security by providing an affordable dietary source of nutrients mainly proteins. The thesis main objective is to contribute for a higher cowpea production in Europe, anticipating the upcoming climate changes. To achieve this goal, multidisciplinary approaches were undertaken involving field trials and molecular genetics, physiology and biochemistry approaches. Regarding genetic diversity, the morphological and agronomical characterization of 24 Iberian Peninsula cowpea genotypes was performed, thus emphasizing the high genetic diversity among genotypes. From this characterization, ten cowpea genotypes were selected and further used for determining the stability of morphological and agronomical traits in three different environments (two in Portugal and one in Spain), during two consecutive years. A high interaction between genotype and environment was found and Elvas (Portugal) revealed to have the most appropriated environment for the production of this set of cowpea genotypes. The recently developed Cowpea iSelect Consortium Array (Illumina, Inc.) provided an excellent opportunity for further determination of cowpea genetic diversity. This array contains 51,128 SNPs and was used in a set of 96 cowpea genotypes, 43 of which from Iberian Peninsula and 23 from 22 other worldwide countries. Cowpea genotypes were clustered in four subpopulations, mainly differentiated by their geographical origin, allowing the suggestion of a new hypothesis about cultivated cowpea dispersion routes. Most of Iberian Peninsula genotypes and those from other Southern European and Northern African countries were grouped in the same subpopulation, indicating a high genetic similarity among them. However, three Iberian Peninsula cowpea genotypes did not belong to this subpopulation, being two of them classified as ‘admixed’ and another from a different subpopulation. These genotypes could be considered as interesting sources of diversity for future cowpea breeding programs. To get new insights on cowpea drought stress responses, the selection of the best approachesfor screening cowpea genotypes with enhanced drought tolerance is fundamental. Four cowpea genotypes (two Portuguese and two international tolerant references) were submitted to three different watering regimens, during 15 days. Several physiological, biochemical and molecular approaches were tested, revealing that stomatal function parameters, free proline and anthocyanins contents were the most effective in discriminating cowpea tolerance levels. Furthermore, two drought-related genes (VuCPRD14 and VuHsp17.7) were identified as the most effective for drought tolerance selection. For screening cowpea genotypes with enhanced drought tolerance, a worldwide collection of cowpea genotypes (58 genotypes) was tested for seed germination, seedling emergence and proline content under different osmotic potentials. A total of seven drought tolerant genotypes were suggested, which could represent starting material for future cowpea breeding programs. This thesis gave a good contribution for increasing cowpea production in Europe, being the selection of more productive and drought tolerant genotypes the first step. These genotypes could be integrated into breeding programs for enhancing cowpea resilience to climate change. Furthermore, the methodologies tested and proposed in this study allow an effective and fast screening of cowpea genotypes drought tolerance. |
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